1. Field of the Invention
This invention relates to thrusters for spacecraft, particularly compact thrusters.
2. Description of Related Art
Most micropropulsion systems in use today consist of cold gas thrusters which use propellants stored in gaseous form such as molecular nitrogen or helium. Gaseous propellant is stored at high pressures (10's of GPa) in volumetrically large, heavy titanium or graphite composite tanks. The propellant storage and thruster nozzle are typically separated by a complex valve system and perhaps a pressure regulator to reduce the gas pressure to the nozzle. Because the propellant is stored at very high pressures, the valve is typically very large in size to reduce valve leakage. These valves also typically require several Watts of power to actuate. The nozzle throat diameter for a cold gas thruster for a microsatellite mission can be on the order of 10 .mu.m. This makes the cold gas thruster susceptible to particulate contamination plugging of the nozzle. For variable thrust missions, the operating pressure of the thruster can be regulated; however, this comes at the expense of efficiency in terms of specific impulse or thrust per unit propellant mass flow.
In other prior art is U.S. Pat. No. 5,836,150 to Garcia (1998) which relates to micropropulsion but by combustion, with attendant problems of corrosive gases at high pressures in the thruster.
Accordingly, there is need and market for a compact thruster that overcomes the above prior art shortcomings.
There has now been discovered a compact thruster that is capable of efficiently operating over a wide range of thrust levels.